Method and apparatus for motion field storage in triangle partition mode and geometric partition mode

1. A computer-implemented method, comprising:

determining whether a first uni-prediction motion vector for a first partition of a block and a second uni-prediction motion vector for a second partition of the block are from a same reference picture list; and

storing a motion vector for a subblock located in a bi-predicted area of the block,

wherein when the first uni-prediction motion vector and the second uni-prediction motion vector are determined to be from the same reference picture list:

the stored motion vector is the second uni-prediction motion vector,

the same reference picture list is a first reference picture list, and

wherein the second uni-prediction motion vector is stored for the subblock regardless of whether the second uni-prediction motion vector has a reference picture that is also in a second reference picture list different from the first reference picture list.

2. The method of claim 1 , wherein when an absolute value of a weight of a luma sample in the subblock is smaller than a threshold, the subblock is treated as being located in the bi-predicted area.

3. The method of claim 1 , wherein when an absolute value of a weight of a luma sample in the subblock is greater than or equal to a threshold, the subblock is treated as being located in the uni-predicted area.

4. The method of claim 1 , further comprising:

in response to the first uni-prediction motion vector and the second uni-prediction motion vector being determined to be not from the same reference picture list:

combining the first uni-prediction motion vector and the second uni-prediction motion vector to form a bi-prediction motion vector; and

storing, in the motion field of the block, the bi-prediction motion vector for a subblock located in the bi-predicted area of the block.

5. The method of claim 1 , wherein the first partition and second partition are:

two geometric partitions, or

two triangle partitions.

6. The method of claim 1 , wherein the stored motion vector is one of:

a motion vector from a top partition of the block;

a motion vector from a bottom partition of the block;

a motion vector from a left partition of the block;

a motion vector from a right partition of the block;

a motion vector for which a reference picture is closer to a target picture corresponding to a target block;

a motion vector for which a reference picture has higher quality; or

a motion vector with a smaller amount of motion.

7. An apparatus, comprising:

a memory configured to store instructions; and

a processor coupled to the memory and configured to execute the instructions to cause the apparatus to:

determine whether a first uni-prediction motion vector for a first partition of a block and a second uni-prediction motion vector for a second partition of the block are from a same reference picture list; and

store a motion vector for a subblock located in a bi-predicted area of the block,

wherein when the first uni-prediction motion vector and the second uni-prediction motion vector are determined to be from the same reference picture list:

the stored motion vector is the second uni-prediction motion vector,

the same reference picture list is a first reference picture list, and

wherein the second uni-prediction motion vector is stored for the subblock regardless of whether the second uni-prediction motion vector has a reference picture that is also in a second reference picture list different from the first reference picture list.

8. The apparatus of claim 7 , wherein when an absolute value of a weight of a luma sample in the subblock is smaller than a threshold, the subblock is treated as being located in the bi-predicted area.

9. The apparatus of claim 7 , wherein when an absolute value of a weight of a luma sample in the subblock is greater than or equal to a threshold, the subblock is treated as being located in the uni-predicted area.

10. The apparatus of claim 7 , wherein the processor is further configured to execute the instructions to cause the apparatus to:

in response to the first uni-prediction motion vector and the second uni-prediction motion vector being determined to be not from the same reference picture list:

combine the first uni-prediction motion vector and the second uni-prediction motion vector to form a bi-prediction motion vector; and

store, in the motion field of the block, the bi-prediction motion vector for a subblock located in the bi-predicted area of the block.

11. The apparatus of claim 7 , wherein the first partition and second partition are:

two geometric partitions, or

two triangle partitions.

12. The apparatus of claim 7 , wherein the stored motion vector is one of:

a motion vector from a top partition of the block;

a motion vector from a bottom partition of the block;

a motion vector from a left partition of the block;

a motion vector from a right partition of the block;

a motion vector for which a reference picture is closer to a target picture corresponding to a target block;

a motion vector for which a reference picture has higher quality; or

a motion vector with a smaller amount of motion.

13. A non-transitory computer-readable storage medium storing a set of instructions that are executable by one or more processors of a device, wherein the execution of the set of the instructions causes the device to perform:

determining whether a first uni-prediction motion vector for a first partition of a block and a second uni-prediction motion vector for a second partition of the block are from a same reference picture list; and

storing a motion vector for a subblock located in a bi-predicted area of the block,

wherein when the first uni-prediction motion vector and the second uni-prediction motion vector are determined to be from the same reference picture list:

the stored motion vector is the second uni-prediction motion vector,

the same reference picture list is a first reference picture list, and

wherein the second uni-prediction motion vector is stored for the subblock regardless of whether the second uni-prediction motion vector has a reference picture that is also in a second reference picture list different from the first reference picture list.

14. The non-transitory computer-readable storage medium of claim 13 , wherein when an absolute value of a weight of a luma sample in the subblock is smaller than a threshold, the subblock is treated as being located in the bi-predicted area.

15. The non-transitory computer-readable storage medium of claim 13 , wherein when an absolute value of a weight of a luma sample in the subblock is greater than or equal to a threshold, the subblock is treated as being located in the uni-predicted area.

16. The non-transitory computer-readable storage medium of claim 13 , wherein the execution of the set of the instructions causes the device to further perform:

in response to the first uni-prediction motion vector and the second uni-prediction motion vector being determined to be not from the same reference picture list:

combining the first uni-prediction motion vector and the second uni-prediction motion vector to form a bi-prediction motion vector; and

storing, in the motion field of the block, the bi-prediction motion vector for a subblock located in the bi-predicted area of the block.

17. The non-transitory computer-readable storage medium of claim 13 , wherein the first partition and second partition are:

two geometric partitions, or

two triangle partitions.

18. The non-transitory computer-readable storage medium of claim 13 , wherein the stored motion vector is one of:

a motion vector from a top partition of the block;

a motion vector from a bottom partition of the block;

a motion vector from a left partition of the block;

a motion vector from a right partition of the block;

a motion vector for which a reference picture is closer to a target picture corresponding to a target block;

a motion vector for which a reference picture has higher quality; or

a motion vector with a smaller amount of motion.